SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '509e191e7bcc915e5bc1bf09be11a746e42822ea80894e3ac1d4b0610644e8cd' 
  AND token = 'NkveHFECYFbZ+aN06R+liv4o+D9W7mNuvjT2AsQzkVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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