SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a8ba7262e4586232514d0b9aae518b19319f514b764fc478ebb1bc654089cba' 
  AND token = '0rxfuLoK5mZTdql8VL4d8bHVQ1XKYpOUd/rIJ3U+kMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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