SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ce8cc127c6874e4e7628aef6ef427dcd0681edd2a7f525b323393639eb2f500' 
  AND token = 'OwKuKrLBtjvI1JnKESkVigRxbwH/y2TgpuhJu/BwYQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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