SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffe362a31f41dc120622e38b03719648baee873a34905dc50dc3e4048feae85b' 
  AND token = 'w/D7oQZSItbnwmc9jSzCd7SBqFPCSzQvZWn6pnBEsrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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