SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc1cd272a1c5d1349a3d8cc1c43a2fa619bb98a48a16e407020aab2e50882d81' 
  AND token = 'C8sOYpPgFg4kjEbBd8tzmwQuzIyB1CCdkwmBMH079Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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