SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '284bde7e88512f420c74d78fa2ebb380d9b317208363c904c4b2f649eff0331f' 
  AND token = 'iB6//BIUCyLAVKSeZdgfkZnv7Npe2z3tpjlmG7xKCXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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