SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efb68dc13041708120436013be086e76115977e8d682c9fded6f032647caa0cb' 
  AND token = 'bIJnKTUwWhWtMXcEexXOdACK9mh/K5ZszLdJESFYnZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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