SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1539aa110af3c7fd5cdbeae49231b8192b45367bef3c383616bf5991a2db7b1' 
  AND token = 'R0fDU6jqVxDA5PZ+v4HSLYKyVBOB+daPRZUsW6po/H0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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