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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6141cf8aa4fe65b73dfd486f0452b1249908ae9b8a503b216de5636b4453a86' 
  AND token = 'g/Nw8SU0zT+de6bMZ9DkHKIIOQDnCeXaHYN3glP2BCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}