SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550b813c025542b918c015240d4d6dd1e0471e568883ae6a78fd6188f3fc5cf5' 
  AND token = 'VNmysiq8tMyhJfeJvDTXiCekgzAaZKpkRBbWBHCCsu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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