SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7be87f604c8db276c0398bfec0e2b23810e91ce62d8086baffa3a66838552556' 
  AND token = 'PxvSPqhbH+v4Z7IozxyDb1JUNUSPR9mV0K3iIKQtXog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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