SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f73777f66928f28cdf648bed74fc017738a464bcebbb6517083a13fe61a0152c' 
  AND token = '+H7+8j2iy1QgmmMYyl3qxPAnqHE34OX532iidfosFUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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