SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb544dd3248c49dbc0182d7405272fa15828e881b40455fb6a551e2859358227' 
  AND token = 'nxWvrbsTWyPRXbb79Sx4kUzv8O5tUczOeIKRfyYZsyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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