SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03bd59d8fd2693723a2fa933ec8d681c268a59da03c2aac910dbf0bd67da5c08' 
  AND token = 'mQ5KvcrhfKoA6BIA1YqhvdzXyt2DsdPCG0IyOs2UYsI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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