SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8da84db758fa768aee4ce51468ea18799993b1fb80ea4b7975b66abe9da8bae8' 
  AND token = 'LTT4QJrPrejOup53ngVUUXZ7SLRCNtXu3ACppDrVRBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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