SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d928fade05ab2268067ba8eb95c333fbe240d9fa0b77582379564751a139eb' 
  AND token = 'krGM/0lwJR1GXP0VmpmeZLOxDqVE1PO5VYGJcCVsqqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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