SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ece708a5857aec50399b86a54a3366a69d3ca3c09027d15c45b02c68ba33c434' 
  AND token = 'ZZOn4BJKKCMRZjw5SUZqcw0ghqE1UJrRj8pHfXsC+1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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