SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '863392084b23e6dcc9920788d0404b523e2025324a7359832936fd77451ed5d0' 
  AND token = 'uraMj+fWMm+5CSiJxCJgAFJacSPKZ2UU2F8ZMFRfOpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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