SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136b04688fcf426dd111a851bb750c5c17ea8325040f5b745c70dca951875df8' 
  AND token = 'as0qVNOGuLae3TxXqjegOVIqkFwKA8s1UJdZVQvTXJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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