SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f1961feec4b03897a18d6166d968094fbb7c4253bc4cec4c1fd24665d8e3f40' 
  AND token = 'rFzTOFw4qRiDLAZsaoUOayhaBVrq5SLRaaSaNxFfpVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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