SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b15884de2cf7a8fad4de7dfa4c44e899818016da6e6e2dd131447332704357d' 
  AND token = 'UoUH0B5aKnAa6bZnvopCIqErCNsrpfQ1fred2HCUuaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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