SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cc3f90dcda536653052b3e6f7eb21925425f5f3ad2e90baaf9b28cc894312db' 
  AND token = 'udEDYIPb2bgsIiEZ1PpYFgJSsQ6P7PLsHLsp10PF3nE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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