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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3616c985c7111f6f37d9e9903a3c4f7e8e4aea0de86e3ffc2a54d17d09954505' 
  AND token = 'ahDR4h6YaW6gYWlKQIVGZ9T4kYoRsRZu8OH6vPAESgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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