SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b96fa42ef15525f3dabe0225a8f8bb7071fad8a8b02ad5d2fa82097a66fc427' 
  AND token = 'fKNRCQdKcIfpuo8uxR0IUaiUzBBu+IMjG1gt5jwwqpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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