SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51bdd78bbfcf5817346a2965ee7c19ea6bc5dbeec765f82a9898f363f4697ee' 
  AND token = 'HDkvNX3waVX7uEvr03fABXwETsRw34U+PEuxDWvQn7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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