SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2bce95312c9a2d3a1033d95327c0548603a70536ed792d5039f6a8ff648dd38' 
  AND token = 'pMdepoNI54JMTqByrbcBK0fyXKYTu4mlLap29mM5OO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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