SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcbcf1c0e91bc4ccc242cdca22d21411b025972711d8dc2c1b454dff613fa871' 
  AND token = 'Qr1vAU0UA5xyjxR8L5XK8vnP/gtsNdqKTp0NtiXRrOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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