SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1c8fd0cac2ba4a91847f42105d8495d806be584b8e9850ff15ad6c6a44c9167' 
  AND token = 'L0p4yEG8psjAvjZEdrBS1NkY4tj0GqnG66wc9ClshUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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