SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8285b64064a1a6f58b2d4794364886bde856901bb9e62c5f632693dc336f250' 
  AND token = '+rg0xInLOa7zCCSTreMXDidk+u3s+yuZDze6HJsxEvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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