SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7619152b310d668589eb6066b9e2dca09a2c3acb1483a99809f5b46b066d0367' 
  AND token = 'pn9FT35tMT7w/wBMF34xn2dXob4zrxIwvpt8yLvCx2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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