SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42670a50f434490c16c2ed86df321a792a68fedce5dddb2795b1ef96e5a56873' 
  AND token = 'RoSFlHaA2hO0MRGYeB1JuFGUwbNIUoImEjoJ5TSH434=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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