SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7635a5972e6ddfdb61154cf7fc8c1e605dbddf1f22dcc34138f96083ea614dd8' 
  AND token = 'EGRBQiR2CMqWY+2Xz9tCQg6PuNIViBLBNw4AOBoymz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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