SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd235bc7a19bc8286cea9f0689552fb47cc27a8a0aa35e15bee094727f09fb253' 
  AND token = 'aOvymCPgKYe4jbItpSTC6ldKZKkwdbZSt4MrochtjfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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