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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a040f1dc59ab9099330d50d17d53c7075b1db547f156c8e58e36a88b1e8f40a6' 
  AND token = 'ZnN/ER+YwhiYcZjL6baNyfmG5xOhgQWZSzE7DutDEiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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