SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31a160e640613d2c086389b75750e43c194e78cd90d09e195b51a1f9a7b28ebb' 
  AND token = 'cRZlGPLSkVD7VRZvL3A6Kqg3K+hGXvvsIuJ7I9KXtmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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