SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1dcebf60c492970d37e090d8224e30e1f00df7d716c982015951641de23aec41' 
  AND token = '5dsIYAVaEGhAfiVPb28n7exOGNqUMG/y1dIpWmWb0Hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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