SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a50d24d8d872c145672789bd9ff035cd657422e40fe6bc1953491def86d9891' 
  AND token = '3FBDzwG7woK/M931Gi2CsCtOE9phj9ysOEGDasMjczE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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