SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2777e06ac190cdb16255ebe5cd5746a8baf577d2e7143101a561d3fcb660af8' 
  AND token = '/u9zInqgVvWKJDhPF1h+uA2IjBziVn18H57OOEXUD9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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