SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6671b1aa384142678c09608cf7441a0182e1e5ed287636aef10045d065b346c' 
  AND token = '5eTTo9Sn6bhzcExTgRnPAikgf5I/DnB1NBcYcCGU4lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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