SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54d31f595e2e8495dd121f742f5f4038d48b3b120d70ae6cfa9227b4e3002c2c' 
  AND token = 'p/ua+Nfnj1WU9TDvKIJYPOmUhrGPBXANzM7+3TWXvtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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