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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd667012c66130aaf3bfc0d70ff56c854f10f4851bb971b0da45aa75ed04eb7a2' 
  AND token = 'vBhGoJZ9uRCktyhyCQD+sPiwQT7YZM+nrc05cOr0YeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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