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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d47812b120f78a0d9b15ca72ec1f94b77cbc54fbb3b6d7e7b03a67e99f0303d' 
  AND token = 'UknG9ble//Dfzx9vkeBIVlmJQvOKM4nuS60d+xWW3Uk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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