SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f82e707b7964ab2f4e1691944f0fd717d6f4f750380e8d31b784ac61e4f85c3' 
  AND token = 'LsLDqjUNzarnBQKOAfrZcHfDWmDxVIdedz8liRpq2/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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