SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08e57c5618d94e2ba5970d936428e3141d42e30583b97f1abc459b3bec390f29' 
  AND token = 'MgD0VXvSHvFKmtbHlenozXenPyA8BRMSgN6RCYKfAPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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