SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '42af2a1f7432b9f2eac03c027b13bb813d79ff16767823de9f3dac330e46ba3e' 
  AND token = '30UxYd41NyL4K2lFq78SEx72E88kH4lO3qlCaHGDRbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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