SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50d6830df29055502165f28ec4117180d47cf31a0c047fa52425129ff104606' 
  AND token = 'QFWRp2IryL/UZCKCZqfQiy1ImU85UwcZ/RGxS7r/wX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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