SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9dd05c482a0d8811981341165b92be578bd897bbdec711aaf5823ef79c7af4d' 
  AND token = 'fhekEndvy3jqlU03ei4hO/sQz2limBQp+BJ0Ac2zeeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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