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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c76b1226fbfef715b2d37dc71d126a1ccc562be6849bb58d713b7a998dafb271' 
  AND token = '11rL0sbTIFzvaMMb85NcnMMvc3hH9ZrqDh4gMYHm0hM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}