SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66d5e9b73cd5abebd7b2eb6287d2e421c2ed78a542e0ae61850430946180ad3f' 
  AND token = 'AdCd1MB8KH4UnOLVS2/gapDQyPU8BuUr02SMRTi5i74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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