SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc35a3148a18af188350bae01260dcbecdffc58cc9627aefa37f4f00d8382a0' 
  AND token = '5m/2t+cBySZ4+4VuKWIesflG5qjwDFm++3YVPwvgiDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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