SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '558bfefc47ca168252e3a6e1a47b6b398af4ca084b8d400f19201ad8e1c0eaef' 
  AND token = '4e9khxebAfGUlcmhqUo7aMIuityQO2hgjU4LcnEmWMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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