SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78c7b63c4c72699027d5faad92a0cde1b326f197a3679e457429c6f7ce7fe13' 
  AND token = 'D1NrKvGoNjCyn4qm/GsY6+3SHxbXvKXhHPS5Lz4I5Ec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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