SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4d8f23e29bb1d4b759b7b847becfdcf4e1315f90031e88694606a44c3eaedb9' 
  AND token = 'NcSdzdh8nAKNzZybZpn+aydXydzbnvDqHh9AcUlSZAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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