SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c950308925be525d0994243d82f1668acd7b6852499fa016ba589c4bf91923b0' 
  AND token = 'a5gUmRl2m1Up8TymgGb5pPP58UuyQOkZJfPoUdpWoK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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