SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '901b9733c8da4e71a04983c20b136c8d171c43d33c0f2f94c1827f52b4b240e8' 
  AND token = 'l/IIn1fzSmbAgQ077e/0Qdom0hHsBu0dwHTJG1BFOCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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