SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b73f3c7e71e795e8fecebb998479467b1ba00b1acb330030387206e3dcf91d6' 
  AND token = 'k++ACBiCUVhFeSqDWOOJl5mDoZ7TuefjoFGTB5oStmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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