SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a093c5fd26d533ebdf48cbe1e73ce1153a508208cc230c36bed32da47c46b3c' 
  AND token = 'bYBx3qiuvMC/CrlzoP/DLc+LSkrDe1eCFpfCcwAKeQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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