SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426fe6b4786fd54c62e18756c96eb0e51f0b55f2f008a2f03bcbb41e214a8a93' 
  AND token = 'hcT0JZzPXE/B5IEqfTlMc7xd1Gv4dvsNvqSUDsdsXV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}