SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8b7e011eb691a581b1db544dab6201b30cd11f5942e107b004d70344470bdeb' 
  AND token = 'KsNQQITapVFXfRMoYTNqTE/UtbFRGPENSjwidgNosQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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