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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b4034a3f08e0d48d80b2e95cbffeee409d3e82f7d33b92a2094ad417fbf8b8' 
  AND token = 't4C7TBbfp5CoqYTgG0E7e1TXHDxpj6pqWwbCV+kUZOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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