SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550a1324908a75e00c3d0cb7169dd8da5e9b5422bf7a0fc1e92d9b1d4aff4b4b' 
  AND token = 'WZO8ZCTMvxnJDv/ktfOkYFBklmW7jQWZisfyOepMaQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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