SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b8efea0921ebc14ab4791d4aa3e4259f10d479566d9293787cdb599066ff4df0' 
  AND token = '5EV1STBif4KgtCJ0gSFdP2faECA02k/SwexV2931nNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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