SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89fe3f882afa24dfd5f290e390e1d36147b2eb9c7a7e148790049515252870a2' 
  AND token = 'FnGsAkBs+EoWxBvj+l1TlYnR4rpjimoTZQxzdnqLmfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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