SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '983c770e82eab4d9f8ade5b8a7584b5adab091a58a3b1c920f00ddba74185765' 
  AND token = '5m82uU3vnxMKeh9r2g+CZyF0zNagxSqtulPvixm1Lu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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