SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9337b3c0ce80045d072d245e48dca3d086169d706b1f2f96380267473fb644fc' 
  AND token = 'iY/Sly4uoGS1eWbIsnykPGNdIE9vGAkEdYvHTyYbfsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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