SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39efc7298937aa81836a1f6636b035ade9bd4e2a2335c385c14426d14678eb1f' 
  AND token = '5rvB9ZcI+GRTDXfUALldVAP93he6FVBnzVfZwrZhRCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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