SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8694fac566913973e8e062b12d3c33f945c0e6209a5f6e7d72a0981ee0220be7' 
  AND token = 'Yns9IPzpfh+K+ueP2NCNVLNHtDQcMOwCvxFIfwtO98Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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