SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58a2f6e9384de916059d09bfa13d79811e22695fa7b856d2f3ce77267e55c3f5' 
  AND token = 'P+EFWyKjXMqOQg9gUdYQfYFz27EE4ifCcJR3vIGTIjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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