SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d51222782693e093e97834e3f3e5a492b54931d7bcd93d325e4226bbc03438b' 
  AND token = 'OmvuL5CdxH5HowQ+/GL/ZnQVGWbb77yYVZzypjNuaYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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