SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c908f840ae8fa0c5b28b164d0e6b3f185814ea44f6839e89dd4d6c67bd777df6' 
  AND token = 'YX2zRNi2AQVaMCiyMR7sOUJAQRWeSpGUJrj8XFEh8GE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}