SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '341ca3b870bbbca387c0af558904a66bc125258174dabd0db38f0c41a05808d3' 
  AND token = 'U6zQsf7p7sMcVuKpWYgpEUtC1Lzd2zAKANsLT/UxXEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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