SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a4b9251e209e87a91609cf66cc4d2771981d8dd34898078eedff0ce96330468e' 
  AND token = '3a93euIF/frofFs9HXPYFDQa4k41Xrx3MunpP2kgbL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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