SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf253aa075ebc1981a0e976b512d1741b8782f461df851f4ebebeee5a7dd6797' 
  AND token = 'owkzDrG+soqm2jUp4TROBVsaQEgAUsKtiS8zSnpSvvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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