SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2e1a383d5fe08d5d90e72d043424e53ebe259d6be6c518ee25644623b3dfeb6' 
  AND token = '9cj/xj74FEtwbreddf7Abh9KmBBa+FhSh5Yr3Ku8ffU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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