SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a8698b4d45fceea2b3f00c073299fdc1f32402d1ae05ba523cf2765b8163d6e' 
  AND token = 'wD5073ykUsm7Xn6uaivNMk3y+paYPNJDUszTeVpKQq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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