SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c443e4155df49913be82d3e3ff2c678bbb4644f316a2e822d9002b65e8abc29' 
  AND token = 'xY4c5BY5/F3ulXcvh+AJPztpcxbdhZBadES1mS0I9MI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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