SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7698426612f489b392384152c63ec7c3009c2eeb84d148ba241963ab6c95a104' 
  AND token = 'rBmyoQxOcnfZAFMAjdgrMGWkxiwY+HRrhnSNShYmFpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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