SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2991844c799f4fe5ad51a1256528a0cf6c6f1cfaedbc8777491c8e430d307f73' 
  AND token = 'tpENbOYJvPKUgKhMEQSWaC4T+Q8NUFmrBuIyYH66chM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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