SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e955a38902afb97e0bbbffdf8599c9b46516f51c47a4fec689881ca0b348b83d' 
  AND token = 'JkZ5Mj9pLNDq09eBIqvq0NCP+BYR7CKv7gXWPJJau2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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