SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8f6282026c5e568278b025ee47c3d9bd95b93692f279403c2e4e0388b48c256' 
  AND token = 'oh+LXQlDxL9kiDiYWu9/dCeYCBvCkrXYeAacq+1HLic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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