SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90dbf19682b8b4d823509486d211bbb259f95990ee21609c1a9d2a7c4b4184a0' 
  AND token = 'tnf3ROIo/PEQS1VkPi002fkRbvgDcVAEadlTT8jW5Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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