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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4a3e28e68e5f6a8be5010af3ed32a35abf2eb67170e50e0feaa4b835d6adb21' 
  AND token = 'EHfXk3M7PfqlXIa4VIjXFqaF+sN0yZco0NFsTMmx6VA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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