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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de81be6189bbcf2cbb75ad3a431819ba65683936ab69b3fdd47a44569937b1c5' 
  AND token = 'Qh5EWnRmzi8q/hC3LzXhHDlSJ3uvLy6TJyfkNhPLu5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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