SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6041284249177767c157cf1bc33181194508ba3c643f6ca5555fbabab2815fe' 
  AND token = 'qWMMqHW9Zw5njnIjyNULZfoBmWp9kChaGcctgJaVOqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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