SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14ffe869d85a1ad01f0473fcb005288b907f6baad3dd38bd0b3087a8d420c571' 
  AND token = 'y2/tl8e2sSgULQMtqitKprZeMSXhxcuc+NQridWMs2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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