SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '16a20270277d10f00201636b7a71cf5e49c436b04f98089faca123fb6e9b8950' 
  AND token = 'N4czBIKypJDw/YjvKf5fTLxF6rMJn4jmkq6E5lfSdBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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