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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1a80359e14642b52fa0a756960e23bb3316ef6b66b3a01e520e71ecdf172844' 
  AND token = 'Hw8Efl0cgIFBh+4wn0hPUEs6SGlED48XuqMaZe9+G3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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