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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca4d3af47e4acbbe44ba81ac62c7dd9b589d8b0403be028fdde5ce786446bd83' 
  AND token = 'rBJ6X7k+rIMVQ17N6AzWb0e6yMR/eF8VHPnBC1zQ6Ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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