SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e55ef2237bbfca3848b76bfee893349a79f9488957b583813120da09d6901722' 
  AND token = 'zQPuIStSUWT1uFAf6NgEHMIdUZdsPs2DwWGZECsASl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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