SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '680c883d908581a3c720d627272801252284904b8080f8ae79fca844f5c0bc77' 
  AND token = 'rU3Y1WJslX/DYNjMcbJR3I2VurNl6NdFvpjBpovDWgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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