SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78a2aba7edd147fe448bfc8c8dba695442818eabe5a0c53e1b0d236137b161f3' 
  AND token = '+lK2hkbxvJHaHmBJ/9VGv/A+z0VJVZJME2fUiHCjNzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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