SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03f087b361b3f026f7e247f3fbd88098f231d47d8665bde8a294f60d12ea5c77' 
  AND token = 'kCSueXgWRHCAgBhp2dXGJ56POdAtYZ0MGMNXzmKQPoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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