SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74e68f021aa78db0bbfbb7a03ddd01024689c2b268a50f2d90c7a859cb7f341c' 
  AND token = 'vHUI0vMJHI1yBdLU0KeOS+ko38kTZkyPVVqkT3w32ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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