SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5a56e8bf56fa470b5200a12bad4e2002a5f55c619217493f365c3c3cb9387cfe' 
  AND token = '7qKfAoWtsC/TzuhldSvmqzGDFvdIsE6v+5oEfvN1AwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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