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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db6d3c3d370e8a27f9d341d90d028df870908e639e1be276d0a5c4de2bcda9f3' 
  AND token = 'Vm6ksiZvy0vHJEWEozkJWJh1VwNDKcgwVCI/+ygmIPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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