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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b85b10d1dc6c8f9838298a9bdd02f4238e2e8939351c7a4ea3b8ee8f0f6abedd' 
  AND token = 'btk1B77g7UnvwDqxUq4fJmUETd3k/LTf++tXUvVuPmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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