SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d8f5a81e190c6d6c954deecd8e1225990997bf1ec4e2775522f0047f84f0c12' 
  AND token = 'IU1o3H2BEk99FsgJ4+Kiw9+CJwsuDpokwgDk9I0piEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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