SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf1d7c78424f07921482400b784014cbc08c4d5efe90c24abdfcf8593bc4bcf4' 
  AND token = 'Axx8r3TvphkyjgQItnvvFFFWQewjmyxm7VWc51A+2mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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