SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63b4612529cee059b96868321e81a495151e5516623ce789671982a2227bcb99' 
  AND token = 'S4cpAJFXXxALvuEj+5JovGZBhpuNsQRdqvByVJsuN0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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