SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3638193059e10d329e5d08e28b94f91db4f0bd96a6971340a296da09663497c5' 
  AND token = 'e7GXZbRaC0GTKZVlbMkPzpQ/qhBRuxYZ8lMpjJIz80g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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