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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab88e3aff9d89213ba26fe6046bb548a779fc6d722b7dcb10df9188a1f24d0cc' 
  AND token = 'ux7cmeUl8Lt3QBTaEWvZ2Ihvtb/yDUnDKU4j21seKo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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