SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dbfe610e560446d779234330e40524b27a78f0abb05389ec040fc0f32c01347' 
  AND token = '+No3Rg0m6PanJzmjCXwcjkHO/7ZRgHSCEZonc4yCUg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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