SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36a5108c61e3cbe95424f30da9f80a8e4a957a4b584b46e9b4872b1e20d879dc' 
  AND token = '3/3eiKS+9TzLEAPVFV+iHQaW6GFmpHqVUKxRUL/CYf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}